Method of producing pure white pigment.



No. 718,555. PATENTED JAN. 13, 1903.

W. G. WARINGr. l METHOD 0I' PRODUCING PURE WHITE PIGMENT.

APPLICATION FILED JUNE 14, 1902.

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WILLIAM GEORGE WARING, OF TYRONE, PENNSYLVANIA.

NIETHOD'OF'PRODUCING PURE WHITE PIGMENT.

SPECIFICATION forming part of Letters Patent N o. 718,555, dated January13, 1903. Application nea June 14, 1902. seria Np. 111,753. (Nospecimens.)

the form of raw materials, as follows: (fr):

crude zinciferous ores; (b) heavy spar, either separate-.from orcombined or mixed -with the zinciferous ores; (c) fuel, and asintermediate (regenerative) agents: (a) an acidulated regenerativeleaching fluid; (b) magnesium oxid and chlorid or oxychlorid.

The process comprises ten operations, namely:

1. The extraction of zinc from ores and other material containing` zinc,by means of lixiviation with a regenerative acidulated solution,described in detail in my application, Serial No. 111,750, filed June14, 1902.

2. The separation from the aqueous product of 1 ofthe metals of thecopper-cadmium group by means of zinc sulid, as described in detailin myabove-mentioned application, Serial No. 111,750, led June 14, 1902.

3. The precipitation of the zinc containedin said aqueous product bymeans of hydrogen sulfid, as described in detail in my said application.

4. The conversion of a portion of the Zinc snld thus produced intosoluble Zinc sulfate by calcination and treatment of the resulting zincoXid with the sulfurous gases produced during calc'ination or With thegases from the calcination of the sulfur contents of the leachingresidues, with subsequent oxidation, or by direct decomposition of thesine sulfid by means of hydrated sulfuric acid in a closed retort.

5. The decomposition of another portion of the zinc-sulfid product of 3into zinc chlorid and hydrogen suld by means of hydrochloric acidin aclosed retort or still, as described `in detail in my application,Serial No. 111,751, -iiled June 14, 1902.

6. The conversion of barium sulfate (heavy spar) into barium suld byfurnacing with coal in a reverberatory furnace.

7. The decomposition of the barium-sulfi product of 6 into bariumchlorid and hydrogen sulfid by means of dilute hydrochloric acid and thepurification of the barium-chlorid solution from iron by means ofchlorin and zinc oXid or barium carbonate.v

8. The'precipitation of the zinc chlorid and sulfate solutions producedfrom 5 and 4 byr means of an emulsion of magnesium oxid with thebarium-chlorid solution from 7 and Washing the pigment so precipitated.

9. The evaporation of the liquor resulting from 8 containing onlymagnesium chlorid and addition thereto of a definite amount oflmagnesia, as describedin my application, Se-

rialfNo. 111,752, filed June 14, 1902.

10. The calcination of the product of 9 for the regeneration of themagnesium oXid and hydrochloric acid, as described in my saidapplication No. 3.

To carry out the process successfully, it is necessary to describe morefully the operations Nos. 6, 7, and 8, in connection with the detailsgiven in my applications Nos. 1, 2, and 3 referred to.

It is not essential that the heavyspar to be used in 6 should be pure.If the residues from the lixiviation in l consist chiefly of heavy spar,they may be used for the production of barium sulfid. The heavy spar isto be mixed very intimately by grinding with Vfrom thirty to forty percent. of its Weight of bituminous coal, according to the quality of thelatter, and ignited in batches at a strong `red heat in an ordinaryreverberatory furnace for one and one-half to two hours or until theflames of burning OO evolved are seen to diminish. The product is drawnwhen finishedinto a closed receptacle in order that it may cool tonearly 212 Fahrenheit without contact With fresh air. The crude sulfidis then lixiviated with boiling Water, one hundred parts of whichdissolves nearly twenty-nine parts of BaS, nearly ninetyper cent. ofwhich is deposited upon cooling in the form of crystalline BaSSHgO. TheliXiviation of the IOO crude sulfid is best conducted in avesselprovided with a filtering-diaphragm with a capacious space beneathcontaining the lower end of an open pipe extending through the filter tothe top of the vessel, provided with a steam jet at the lower end,whereby the liquor as it passes through the filter is forced again tothe top and there spread over the material by means of a concave capfixed over the upper extremity of the stand-pipe. A concentrated hotsolution is thus obtained which may be treated directly with HC1 in aclosed Wooden or stoneware vessel for the production of the BaC12 andH28 of 7. The weaker liquors resulting from subsequent lixiviations ofthe partlyspent crude sulfid are to be reserved for the firstlixiviation of fresh batches of crude sulfid. The completely-spentresidues,still containing twenty to forty per cent. of the bariumoriginally used, partly as carbonate and partly in thi- VAoniccombinations, may be exposed to the action of sulfurous furnace-gasesand again reignited with the coal for the recovery of a fresh amount ofBaS. After the second leaching the residues, now consisting chiefiy ofearthy matters derived from the coal, may be discarded as waste ashes.

The decomposition of barium sulfid by means of hydrochloric acid may beconducted in any closed stoneware or enameled retort or generator, whichcan be heated to the boiling-point to insure complete expulsion of theH28 product. The HC1 is preferably admitted gradually under pressurefrom an elevated reservoir, and only such quantity is to be added as ischemically equivalent to the amount of barium present in the BaSsolution as determined by its volume and density by the hydrometer.

The purification of the resulting solution of BaC12 of 7 by means ofchlorin and barium carbonate or zinc oxid is a well-known operationrequiring no description. The object is to remove any traces of ironwhich may have contaminated the acid or the BaOl2. The H28 resultingfrom 7 is first conducted through a weak solution of BaS to free it fromHC1 and then to a gas-holder, where it is stored for use in 3. Theprecipitation of the mixed zinc chlorid and sulfate in 8 requiresspecial precautions in order to secure a successful result. Thequantitiesof the several materials used must be so proportioned that foreach part of metallic zinc present in the solution as sulfate theemulsion must contain the equivalent of 3.736 parts of BaCl2 2H2O (theresult of the complete decomposition of 3.57 parts of pure heavy spar)and 0.6158 parts of pure MgO, and also in addition thereto a likeproportion of MgO for each part of metallic zinc present in the solutionin the form of chlorid. Thus when the ZnSO4 and the ZnCl2 solutionsproduced from 4 and 5 result from equal quantities of ZnS there will berequired for each unit of zinc present in the mixture 1.868

parts of BaC12 21120 and 0.6158 part of MgO in the emulsion, and theproduct will contain nearly seventy-five per cent. of BaSO4 withtwenty-five per cent. hydrated zinc oxid, or if completely dehydratedits composition is theoretically 74.15 per cent. BaSO4 and 25.85 percent. ZnO.

It follows that the relative proportions of ZnO and BaSO4 in theprecipitate may be varied according to the ratio of ZnS converted intosulfate or chlorid in 4 and 5. Thus to obtain a product containing equalproportions, by weight, of ZnO and BaSO4 1.87 parts of Zn(2.78 ZnS) mustbe converted into ZnCl2 for one part Zn(1.49 ZnS) converted into ZnSO4,and there will be required for the emulsion 3.74 parts BaCl2 2H2O and1.77 parts of MgO.

To avoid the production of oxychlorids in this process, the sameprecautions are to be observed which are set forth at length in myapplication No. 3 of this date.

In the accompanying diagrammatic drawing I have indicated the means usedfor carrying out the method hereinbefore described.

I claim as my invention- 1. The method of producing a pure white pigmentconsisting of barium sulfate and zinc oxid, by precipitating a mixedsolution of zinc sulfate and chlorid with an emulsion composed ofmagnesium oxid suspended in a solution of barium chlorid, ashereinbefore described.

2. The method of producing a pure White pigment consisting substantiallyof barium sulfate and zinc oxid, the components of which may bear anydesired ratio to each other, wherein a solution of zinc sulfate andchlorid containing definite proportions of each salt is precipitated bymeansof an emulsion of magnesia in asolution of barium chloridcontaining so much barium chlorid as is exactly equivalent to thesulfate of zinc in the solution, and so much caustic magnesia as isexactly equivalent to the total zinc contained in the solution, ashereinbefore' described; and the residual solution after separation fromthe pigment so precipitated is evaporated, the residue mixed with abouttwenty-five per cent. of magnesia, and calcined in contact with aqueousvapor for the recovery of the magnesia and hydrochloric acid,substantially as described above.

8. The process for the production of a pure White pigment consisting ofzinc oxid and barium sulfate, the components of which may bear anydesired ratio to each other, which process consists in subjecting rawores or materials containing zinc in any combination, along with heavyspar, either mixed, or separate, to lixiviation with a .specialregenerative fiuid consisting of an extremely dilute aqueous solution ofsulfuric acid and ferric sulfate for the extraction of the zinc, andsubsequent precipitation of the zinc by means of hydrogen sulfld;calcining the residue, or heavy spar, with coal, lixiviatingwith WaterIIC from the precipitated pigment, and recovering the magnesia andhydrochloric acid theredrogen suld and barium chiorid; conversion fromfor reuse, by means of evaporation, of determined proportions of theprecipitated and caicination in contact with aqueous vazinc suld intozinc sulfate and zinc chiorid l por substantiallyvas hereinbeforedescribed. by treatment with the respective acids or In testimonywhereof I ax my signature otherwise, as described; precipitation of thein presence of two Witnesses.

solution of zinc salts so procured by an emni- 1 sion of caicinedmagnesia in barium-chlorid WILLAM GEORGE VARING' solution in deiniteproportions as described; Vtitnesses:

thereby producing the pigment required; A. M. HULL,

separation ofthe magnesium-chloridsolution l GUY H. WARING.

and decomposing the liquid thus produced by means of hydrochloric acidto produce hy-

